The invention pertains to a probe for use with a machine tool having a rotary spindle, the probe being of a type which is not mounted in the spindle.
As is well known, contact probe devices are commonly used with machining centers to automatically measure or otherwise inspect a workpiece during the course of machining operations. An important class of such devices is exemplified by U.S. Pat. No. Re. 30,975, issued June 22, 1982, for a "Spindle Probe with Orbital Transformer". Such patent shows an electric circuit contained within a housing mounted on a conventional tool holder. A stylus extends outwardly from the housing which can be displaced or deflected relative to the housing. The stylus is coupled to the circuit so that the circuit will generate electric signals when the stylus is deflected along the X, Y or Z axis of the machining center. Thus, to measure a workpiece which has been machined by a machining center, the device is inserted into the spindle. The spindle is then moved to bring the stylus into contact with machined surfaces of the workpiece to deflect the stylus and thereby generate signals. The position of the stylus along the axes at contact with the workpiece indicates the extent of material removal from the workpiece, and thus indicates the accuracy of the machining operation.
When a device of the above type is used with a machining center to measure or inspect a workpiece, two complete tool transfer operations must be performed by the tool change mechanism of the machining center. One transfer operation is required to move the probe device from the tool storage magazine into the spindle, and the other is required to move the probe from the spindle back to the tool magazine. In some machining centers, a tool transfer operation requires in excess of ten seconds. No machining can be performed during the tool change operations, or while the probe is in the spindle. Also, it is frequently desirable to inspect a workpiece between two machining operations using the same cutting tool. In such situations, it would be very advantageous to allow the tool to remain in the spindle while the inspection was performed. Time required for multiple tool change operations is thereby eliminated. In addition, precision of subsequent machining is likely to be enhanced, since the seating of the tool in the spindle will remain unchanged.